PYTHON-1714 Add c extension use to client metadata

- Fix FooDriver test

Author: aclark4life

test/asynchronous/test_client.py

@@ -369,7 +369,10 @@ async def test_metadata(self):
         with self.assertRaises(TypeError):
             self.simple_client(driver=("Foo", "1", "a"))
         # Test appending to driver info.
-        metadata["driver"]["name"] = "PyMongo|async|FooDriver"
+        if has_c:
+            metadata["driver"]["name"] = "PyMongo|c|async|FooDriver"
+        else:
+            metadata["driver"]["name"] = "PyMongo|async|FooDriver"
         metadata["driver"]["version"] = "{}|1.2.3".format(_METADATA["driver"]["version"])
         client = self.simple_client(
             "foo",

test/test_client.py

@@ -361,7 +361,10 @@ def test_metadata(self):
         with self.assertRaises(TypeError):
             self.simple_client(driver=("Foo", "1", "a"))
         # Test appending to driver info.
-        metadata["driver"]["name"] = "PyMongo|FooDriver"
+        if has_c:
+            metadata["driver"]["name"] = "PyMongo|c|FooDriver"
+        else:
+            metadata["driver"]["name"] = "PyMongo|FooDriver"
         metadata["driver"]["version"] = "{}|1.2.3".format(_METADATA["driver"]["version"])
         client = self.simple_client(
             "foo",